Re: [PATCH v1 07/11] x86: perf: intel_pt: Intel PT PMU driver

Andi Kleen
2014-02-06T20:30:27Z

> diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
> index 0fa4f24..28b5023 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> @@ -1312,6 +1312,8 @@ int intel_pmu_save_and_restart(struct perf_event *event)
> return x86_perf_event_set_period(event);
> }
>
> +void intel_pt_interrupt(void);

Should be in $(pwd)/perf_event.h

> diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
> new file mode 100644
> index 0000000..b6b1a84
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
> @@ -0,0 +1,991 @@
> +/*
> + * Intel(R) Processor Trace PMU driver for perf
> + * Copyright (c) 2013-2014, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program; if not, write to the Free Software Foundation, Inc.,
> + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.

Remove the address, and add a pointer to the specification

Similar in the other files.

> +/*
> + * Capabilities of Intel PT hardware, such as number of address bits or
> + * supported output schemes, are cached and exported to userspace as "caps"
> + * attribute group of pt pmu device
> + * (/sys/bus/event_source/devices/intel_pt/caps/) so that userspace can store
> + * relevant bits together with intel_pt traces.
> + *
> + * Currently, for debugging purposes, these attributes are also writable; this
> + * should be removed in the final version.

Already remove that code?

> +{
> + u64 reg;
> +
> + reg = RTIT_CTL_TOPA | RTIT_CTL_BRANCH_EN;
> +
> + if (!event->attr.exclude_kernel)
> + reg |= RTIT_CTL_OS;
> + if (!event->attr.exclude_user)
> + reg |= RTIT_CTL_USR;
> +
> + reg |= (event->attr.itrace_config & PT_CONFIG_MASK);
> +
> + if (wrmsr_safe(MSR_IA32_RTIT_CTL, reg, 0) < 0) {
> + pr_warn("Failed to enable PT on cpu %d\n", event->cpu);

Should rate limit this warning

> + return -EINVAL;
> + }
> + return 0;
> +}
> +
> +static void pt_config_start(bool start)
> +{
> + u64 ctl;
> +
> + rdmsrl(MSR_IA32_RTIT_CTL, ctl);

Should bail out here if someone else already started (e.g. hardware debugger)
The read needs to be moved to before we overwrite other MSRs

> + if (start)
> + ctl |= RTIT_CTL_TRACEEN;
> + else
> + ctl &= ~RTIT_CTL_TRACEEN;
> + wrmsrl(MSR_IA32_RTIT_CTL, ctl);

> +
> +/**
> + * pt_handle_status - take care of possible status conditions
> + * @event: currently active PT event
> + */
> +static void pt_handle_status(struct perf_event *event)
> +{
> + struct pt_buffer *buf = itrace_priv(event);
> + int advance = 0;
> + u64 status;
> +
> + rdmsrl(MSR_IA32_RTIT_STATUS, status);
> +
> + if (status & RTIT_STATUS_ERROR) {
> + pr_err("ToPA ERROR encountered, trying to recover\n");

Add perf: prefix here (or better redefine pr_fmt at the beginning)
Should be rate limited

> +static struct pt_buffer *pt_buffer_alloc(int cpu, size_t size,
> + unsigned long watermark,
> + bool snapshot, gfp_t gfp,
> + void **pages)
> +{
> + struct pt_buffer *buf;
> + int node;
> + int ret;
> +
> + if (!size || watermark << PAGE_SHIFT > size)
> + return NULL;
> +
> + if (cpu == -1)
> + cpu = raw_smp_processor_id();
> + node = cpu_to_node(cpu);
> +
> + buf = kzalloc(sizeof(struct pt_buffer), gfp);
> + if (!buf)
> + return NULL;

Should be kzalloc_node()

-Andi
--
ak@linux.intel.com -- Speaking for myself only